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Updated: Aug 19, 2026
Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents
Published on: July 3, 2013
Blocking L-calcium current by l-tetrahydropalmatine in single ventricular myocyte of guinea pigs
1Department of Cardiology, Cardiovascular Disease Institute, Union Hospital. cjhuang@public.wuhan.cngb.com
Aim:
To study the effect of l-tetrahydropalmatine (l-THP) on L-type calcium channel.
Methods:
Patch clamp technique (whole cell recording) was used to record L-Ca2+ current in single cardiac myocyte.
Results:
1) l-THP 1, 10, and 100 micromol.L-1 reduced ICa-max from (999 +/- 93) pA to (700 +/- 111) pA, (582 +/- 66) pA, and (420 +/- 112) pA (n = 6, P < 0.01), respectively. 2) l-THP reduced the voltage at half-maximal inactivation (V1/2) of L-Ca2+ channel to more negative potentials by 9 mV (n = 5, P < 0.05). 3) l-THP caused both tonic and use-dependent reduction of Ca2+ current. Tonic block of l-THP on Ca2+ current was 46% +/- 8% (n = 6, P < 0.01). The degree of use dependent blocking was 13.5% +/- 2.4% (n = 6, P < 0.05) at 1 Hz, the degree increased to 44% +/- 5% (n = 6, P < 0.01) at 3 Hz. 4) l-THP delayed half-recovery time of Ca2+ channel recovery from inactivity from (94 +/- 39) ms to (170 +/- 42) ms(n = 6, P < 0.01).
Conclusion:
l-THP has a moderate inhibitory effect on L-Ca2+ current.
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